Portable electric tool



E. P. TURNER ET AL PORTABLE ELECTRIC TOOL Dec. 14, 1948.

Filed Sept. 13, 1947 2 Sheets-Sheet 1 INVENTORS. 3 121 P Turner Dec. 14, 1948. E. P. TURNER in AL 2,456,571

PORTABLE ELECTRIC TOOL 2 Sheets-Sheet 2 JNVENTORS @Qar Pfz'zrner;

BY Reynalzi fign ve ATTbRNfY Patented Dec. 14, 1948 PORTABLE ELECTRIC TOOL Edgar P. Turner, Fanwood,

Pittstown,

and Reynold Happe,

N. J., assignors to The Singer Manufacturing Company, Elizabeth, N. J., a corporation of New Jersey Application September 13, 1947, Serial No. 773,814

. 8 Claims.

This invention relates to portable tools of the type having an enclosed electric motor, a rotary tool spindle and a train of speed-reducing gears located in a suitable casing and operatively connecting the motor with the tool spindle.

One of the problems in tools of. this nature is the dissipation of the heat generated by the motor and by the gear train. Unless this heat is effectively dissipated the tool will become too hot to handle and the motor will be impaired and eventually destroyed.

This invention has as a primary object to provide an improved and simplified construction, the parts of which can readily be made by conventional die casting operations, for effectively ventilating and cooling tools of this nature and for lubricating the gear train.

Another object of the invention is to provide a simplified construction of this nature having a minimum number of parts which may be made by die casting operations from simple molds which are devoid of side-draw parts.

A further object of the invention is to provide an improved ventilating and cooling system for hand tools in which the ventilating and cooling air is caused to flow more nearly in a streamline than heretofore has been possible and in which the air discharged from the tool is directed forwardly and away from the user.

With the above and other objects in view, as will hereinafter appear, the invention comprises the devices, combinations and arrangements of parts hereinafter set forth and illustrated in the accompanying drawings of a preferred embodiment of the invention, from which the several features of the invention and the advantages attained thereby will be readily understood by those skilled in the art.

Fig. 1 is a side elevation of an improved portable electric drill embodying the present invention.

Fig. 2 is a longitudinal sectional view of the drill shown in Fig. 1, with a portion of the drill chuck in elevation.

Fig. 3 is an inside perspective view of an improved gear casin which forms a part of the present tool.

Fig. 4 is an inner face view of the gear casing shown in Fig. 3, with a portion of the tool-spindledriving gear train therein.

Fig. 5 is a perspective view of one section of a motor housing which cooperates with the gear casing, shown in Fig, 4, to support and house the gear train.

Fig. 6 is a face view of the section of the motor housing illustrated in Fig. 5, showing also the motor housing, taken substantially on the lines of Figs. 4 and 6.

Fig. 8 is a sectional view taken on the lines 8-8 of Figs, 4 and 6.

Fig. 9 is an outer face view of a modified form of gear casing.

Fig. 10 is a detail sectional view on the line ill-l0 of Fig. 9.

Referring more specifically to the drawings, the invention is disclosed as embodied in a portable electric drill comprising a frame consisting of front and rear sections I and 2, respectively, having substantially cylindrical outer walls which house an electric motor designated generally as M. This motor has a rotary drive shaft 3 and is controlled by a switch device designated generally as S, located in a hollow pistol-grip handle 4 forming an integral part of the rear frame section 2. Secured to the front end of the frame section I is an open faced gear casing 5 in the forward wall of which is journaled, in an antifriction bearing 6, the forward end portion of a rotary tool spindle '1 adapted to carry a chuck C or other form of tool holder. The reduced rear end 1 of the spindle 1 is journaled in an antifriction bearing 8 carried in a socket 8 provided by a transverse front end wall 9 of the frame section I. The wall 9 also supports an anti-friction bearing ID in which the forward end of the motor shaft 3 is journaled, the rear end 3 thereof being journaled in an anti-friction bearing ll carried by a transverse portion l2 of the rear frame section 2.

Inasmuch as the specific construction of the motor and the means for supplying and controlling the flow of electric current thereto are generally similar to those disclosed in the United States patent of R. Happe and E. P. Turner, No. 2,396,007, Mar. 5, 1946 and form no part of this invention, detailed illustration and description thereof is deemed unnecessary.

Located within a substantially cylindrical chamber 5 formed in the gear casing 5, is a series of speed reducing gears comprising a driving pinion [3 carried by the end of the motor shaft 3, a gear I 4 which meshes with and is driven by said pinion, a pinion l5 rotatable with the gear I 4, and a gear I 6 secured upon the tool spindle l and driven by the pinion 15. The gear l4 and pinion l5 are mounted upon a jack shaft l l which maintain the chamber 5 substantially filled-with (I grease to lubricate the gears. As shown most clearly in Figs. 3, 4, 5 and 6, a portionof the channel 20 and rib 2| are omitted-from-.r to y adjacent the outer edge of the gear": =Inthat" area, a grease-tight joint is effected between the frame section I and the gear casing 5 bymetale to-metal contact of the flat surfaces I and ;f of the parts I and 5, respectively.

The motor shaft 3 carries, adjacent the bearing l0, 1 fan22 which; during rotation of the'motor,

draws air into the motor casing throughperfora tionsra formed in a grilleplate 23which-covers apertures formed in the upper wall of the framesection 2. The plate 23Iha's'animperforate portion 123% which may serve as a name plate, there by obviating the necessity and expense of provid ing a separate plate for the latter purpose.

As shown by the arrows in Figs. -1 and 2, air

drawn winto the motor casing flows around the 1 stator and through slots s in the armature A, thereby .oooling themotor, after which the air is forced forwardly by the fan 22 and outwardly through vent slots t provided between the gear casing! and the framesection l-. These slots are formed'bycuttingraway or depressing the forwardedge of the frame section I between the lands 1 where it contacts therear facef of thegear'casingfor receptionof connecting screws 24;

To afford a free and unobstructed flow of air forwardly and o-utwardlyfrom the fan: 22, the forward portion of the outer wall of theframe section I is bevelled or flared outwardly and forwardly asindicated at b in Figs. 1, 2, 5 and-6p Likewise the transverse wall 9 of the frame sec-' tionl-l is rounded as indicated at c, surrounding thebearing Hi, to facilitate the free forward-and f outward flow of the air.

As shown most clearly inFigs. 2, 6, and 8, the a fan 22 rotates within, and. substantially fills; a

substantially cylindrical fan chamber B formed 9 in the forward end of the'casing section I. This,

together with thenbevelled or flared wallb of the casing section, greatly increases the efficiency of the fan.

The flow of air through the motor'casing and 9 motor carries away :the excess heat in the motor and maintains it at a safe operating temperature;

The, air streamcreated by thefani22 also serves to absorb. and dissipate a substantial amount of the heat. generated in the gear-casing 5 by the;

action of the gears 'therein.

This is effected by the provision of air chambers 25 in the lower end of the gear casing. These chambers are formed 25 from the gear chamber 5 and 23. A portion of the air discharged by'the fan 22 flows into the open rear face of the chambers-25, contacts the walls 26, 21, 28 and' the rib 29 andpicks up heat transmitted thereto from the gear'casing.

The air then turns, as indicated by the arrows inFigs. 1 and 3, and passes out wardly through the 5101; t between-the gear-case 5 and the frame section I, carrying with it a substantial portion of the heat generated in the gear casing.

In Figs. 9 and 10 there is disclosed a modified form of gear casing in which the forward wall 215 is provided with a plurality of parallel slots or apertures 30, iforwardly of the chamber 25". Air discharged by the fan 22 into the chamber 25" passes through the chamber and outwardly through the slots 30. The walls 31 between the slots '30 serve-as heat dissipating fins which assist in cooling the gear casing.

From ithe'foregoing'it will be apparent that this invention has provided an improved construction comprising onlyp'three elements, viz: the two frame'sections 'l and 2 and the gear casing 5 (all of whichzmaydpe readily made by simple die casting operations) for effectively cooling the motor, for -housingthe speed reduction gears and maintaining them in a suitable lubricating grease, and forwdiss'i-pating the::heat generated by said'gears.

It is to be'notedthat: the cooling air flows in a streamline through the tool and is discharged in a forward: direction and away frorn the user so that the user Gift-118113001 is not inconvenienced or annoyed thereby;

Having thuszset forth-the nature of the invention;:what we claim herein is:

l. A .portable eleotric tool. including a motor casingxcomprisingwunited front and rear sections,-

said rear section having an air inlet, saidfront section comprising a substantially cylindrical outer .wallv and a substantially circular front end wall; formed -integrally with and segmentally spaced'from:said outer'wall, the forward portion of said outer wall beingbevelle'd forwardly and outwardly adjacent a portion of said end wall to afford an outwardlyand forwardly inclined-air passageway; a motor mounted in said casing and having-a rotory shaftya gear casingsecured to i said front sectionbut spaced-therefrom in the region adjacent the beveled portion of the outer wall ofsaid motor casing; and a fan on said motor shaft for drawing airintc said motor casing through-saidinlet -and through said motor and ejecting-it forwardly "and outwardly through the space between the *motor casing'and the gear casing.

2. A portable electric-tool includinga motor casingcomprising-united front and rear sections, said rear section having an air inlet, said front sect-ion comprising a substantially cylindrical outer wall and a substantially circular front end wal1 formed integrally with said outer wall but spaced therefromadjacent the lower half of the circularend wall; a motor mounted in said casing and having a rotary shaft; a gear casing secured to said front section and provided with an open faced gearchamber normally closed by said cir cular end wall, saidgear casing being spaced from the frontsection'of said motor casing in the re-:'

gionadjacent the lower half of saidcircular end wall of said motor casing; and a fanon said motor shaft for drawing air into said motor casing through saidinlet-and through said motor and ejecting it forwardly and outwardly through the space-between the motor casing and the gear casingm 3. A portable electric tool including a motor casing comprising-united front and rear sections;

said frontsection comprising a substantially cylindri'oalouter wall and a substantiallycircular end wall formed integrally with said outer wall 1 but spaced:therefrom adjacentthe lowerhalf of i the circular endwall, the forward portion of said end wall being provided with an outwardly extending arcuate rib; a grease-tight gear casing secured to said front section but spaced therefrom in the region adjacent the lower half of said circular end wall of said motor casing, said gear casing being provided with an arcuate channel adapted to receive said rib; a motor mounted in said casing and having a rotory shaft projecting into said gear casing; a tool spindle journaled in a wall of said gear casing; and a speed reducing gear train located within said gear casing and connecting said motor shaft with said tool spindle.

4. A portable electric tool including a motor casing comprising united front and rear sections, said rear section having an air inlet, said front section comprising a substantially cylindrical outer wall and a substantially circular end wall formed integrally with said outer wall but spaced therefrom adjacent the lower half of the circular end wall; a motor mounted in said casing and having a rotary shaft; a grease-tight gear casing secured to said front section and provided in its upper portion with a substantially circular gear chamber normally closed by said end wall and in its lower portion with an air chamber; and a fan on said motor shaft for drawing air through said inlet and into said motor casing and through said motor and ejecting it forwardly into said air chamber and finally outwardly through the space between the motor casing and the gear casing.

5. A portable electric tool including a motor casing comprising united front and rear die-cast sections, said rear section having an air inlet, said front section comprising a continuous outer wall and a substantially circular end wall formed integrally with said outer wall but spaced therefrom adjacent the lower half of the circular end wall, said front section being provided with a plurality of bearing sockets; a motor mounted in said casing and having a rotary shaft; a die-cast gear casing secured to said front section but spaced therefrom in the region adjacent the lower half of said circular end wall of said motor casing, said gear casing being provided with a plurality of bearing sockets, each aligned with one of the sockets in said front section; a tool spindle journaled in said gear casing; a gear train in said gear casing journaled in bearings in said sockets for connecting said motor shaft with said tool spindle; and a fan on said motor shaft for drawing air through said inlet and into said motor casing and through said motor and ejecting it forwardly and outwardly through the space between the motor casing and the gear casing.

6. A portable electric tool including a motor casing comprising united front and rear sections, said rear section having an air inlet, said front section comprising a continuous outer wall affording a substantially cylindrical fan chamber and having a substantially circular end wall formed integrally with said outer wall but spaced therefrom adjacent the lower half of the circular end wall, the forward portion of said outer wall being beveled forwardly and outwardly adjacent the lower half of said end wall to afford an outwardly and forwardly inclined air passageway; a motor mounted in said casing and having a rotary shaft; a gear casing secured to said front section but spaced therefrom in the region adjacent the lower half of said circular end wall of said motor casing; and a fan on said motor shaft operating in and substantially filling said fan chamber for drawing air through said inlet and into said motor casing and through said motor and ejecting it forwardly and outwardly through the space between the motor casing and the gear casing.

'7. A portable electric tool having a motor casing comprising separable front and rear sections having side walls together providing a motor and fan chamber, said front section having an integral end wall of which a portion is spaced from its side wall to provide an air passageway; a motor disposed in said chamber and having a rotary shaft journaled in said end wall of the front section of the casing; a gear casing having an outer wall abutting said front section and provided with an inner gear-housing wall complemental to said end wall of the front section in providing a continuation of said air passageway between said inner gear-housing wall and the outer wall of the gear casing, the outer wall of said gear casing having a portion thereof spaced from the front section outer wall in the region of said air passageway; and a fan carried by said shaft at the motor side of said end wall of the front section.

8. A portable electric tool including a motor casing comprising united front and rear sections, said rear section having an air inlet, said front section comprising a continuous outer wall and a substantially circular end wall formed integrally with said outer wall but spaced therefrom adjacent the lower half of the circular end wall, the forward portion of said outer wall being beveled forwardly and outwardly adjacent the lower half of said end wall to afford an outwardly and forwardly inclined air passageway; a motor mounted in said casing and having a rotary shaft; a gear casing secured to said front section but spaced therefrom in the region adjacent the lower half of said circular end wall of said motor casing, said gear casing being provided in its front wall with a plurality of ventilating apertures; and a fan on said motor shaft for drawing air through said inlet and into said motor casing and through said motor and ejecting it forwardly through the apertures in the wall of the gear casing and outwardly through the space between the motor casing and the gear casing.

EDGAR P. TURNER. REYNOLD HAPPE.

No references cited. 

